Studies will be continued on bacterial substances which induce murine macrophages to synthesize and release immunoregulatory mediators. The bacterial substances include lipopolysaccharides, peptidoglycans, muraml dipeptide, lipoteichoic acids and bacterial membrane proteins. One aspect of the research is to indentify membrane receptors in murine macrophages which specifically bind the bacterial inducers. We are also investigating the mediators produced by macrophages following induction. Some of these are detected by their ability to block the immunosuppressive effects of glucocorticosteroid hormones. These are being purified and their effects on various types of cells is being investigated.